The Washington Post headline was certainly provocative — and definitive. "Obama: The most polarizing president. Ever." As in, case closed, no argument, and explicitly indicated by the evidence. Some might agree with that assessment even without evidence … and they'd have to do so, because the Post's headline writer made a claim that couldn't possibly be reconciled with proof.

Before we debate the issues of polarization, we should note that the article itself didn't support the claim, nor did it make it. Barack Obama has the dubious honor of having the highest differential between Gallup approval ratings in his own party and those in the opposition party for a third year in office, which is a fairly limiting distinction. In fact, he had the same differential in 2011 that he did in 2010 — 68 points — which indicates a certain amount of stability in the polarization.

Presidents are products of their times, not drivers of the underlying currents that raised them to leadership positions.

However, even in the narrow paradigm of Gallup polling, the claim of "most polarizing" doesn't match the table provided by The Washington Post. The top three slots for highest approval differentials all belong to President Obama's predecessor, George W. Bush. Bush takes five of the top 10 positions, as a matter of fact, with Obama's three years finishing fourth, fifth, and seventh. If one uses this gauge as a credible measure of polarization, then clearly the previous administration experienced significantly more of it than President Obama has, and Bush's domination of the top slots would give him the title.

Still, this is a silly claim to make for a number of reasons, chief among them history. Historically speaking, any such claim is rubbish on its face. Abraham Lincoln's election in 1860 was so polarizing that it became the catalyst of the Civil War that raged for four years and put hundreds of thousands of Americans into their graves. Richard Nixon's involvement in Watergate provoked a constitutional crisis so grave that its effects can still be felt in partisan politics. Even Bill Clinton's impeachment created partisan grudges that have echoes in today's Beltway trench warfare. The notion that the current political situation bears any sort of relation to those poisonously polarized times should easily be recognized as unserious mental doodling at best.

That doesn't mean politics has not become more polarized over the last decade. But the presidents involved should not get full credit or blame for that development. America has taken some heavy shocks in the past 20 years, and that engenders polarization. In that time, the U.S. military has fought three wars — the Persian Gulf War, the war in Afghanistan, and the second war in Iraq. The latter two wars became protracted affairs, and while both have remarkably low casualty rates when compared with other American conflicts, the lack of clear goals and framed victory ideals makes the casualties we suffered all the more provocative.

At home, terrorists managed their first full-scale attack on the U.S., the first such attack by an enemy on our native soil since Pearl Harbor. The aftermath brought a massive expansion in national security, creating a sense of mistrust of what the government might do with the extra power it gained. On top of all that, Americans suffered a near-meltdown of the financial system, with millions of people thrown out of work and no prospects for improvement. And finally, we have national-debt and entitlement-financing crises that threaten to make 2008 look like a brief midday shower.

What happens in a crisis — and especially in a series of crises? People tend to revert back to first principles, and defend them mightily. Nuance and caution take back seats to immediate action, sometimes for very good reasons and good effect, but the impulse does not usually involve consensus and group hugs.

This brings us to the underlying fallacy of the Post's claim, which is supposedly based on the two political parties — and an assumption that they are static. They are anything but. Both the Republican and Democratic parties have had decades-long shifts in political temperaments in their own search for first principles, starting with the Barry Goldwater candidacy in 1964 and the New Left's arrival at the Democratic convention in 1968. In short, for almost 50 years, both parties have been changing in fits and starts from their traditional big-tent geographical roots to more ideological organizations. Where we once had plenty of crossover in Congress between blue-dog Democrats and Rockefeller Republicans, the politicians have now affiliated themselves to party by ideology. There has been a remarkable growth of division on non-unanimous votes, especially in the Senate.

It would be foolish to believe that elected officials have partitioned themselves off ideologically without having voters already do the same. Pressure from grassroots activists in both parties has transformed Republicans and Democrats into conservatives and progressives. There are still plenty of subvariants of both, and a spectrum within each group. But over the past 20 years, the notions of "conservative Democrat" and "liberal Republican" have taken on a sepia-tinged patina, a throwback to a bygone era.

There is something to be said for this development, as it tends to focus on actual principles of governance rather than just political expediency. That presents a more honest choice for the voter, even the unaffiliated and/or moderate voter who may not adhere to one set of principles. On the other hand, a little political expediency helps to get tasks accomplished, and the lack of crossover means that more of the routine tasks in Washington end up becoming battlegrounds for larger ideological principles.

Presidents are not disconnected from this process, of course, and presidents have a unique position in American politics from which to help temper or fan these ideological flames. They remain, however, a product of their times rather than a driver of the underlying currents that raised them to leadership positions. As much as we might want to lay the blame on Obama, Bush, or any other president, the actual blame or glory falls on us all.